Defining a straight line in 3D Space ( 6 axis arm)

Thread Starter

Sprayman

Joined Mar 31, 2020
9
Hi all,

This might be a bit simple, (Calculus 3 if i remember right?)

Here is my problem. I am running into a problem when my arm after it grabs something. My parts on on little pegs and the arm isn't pulling the part off exactly straight. I get a torque on the wrist when this happens and the program doesn't like that one bit.

Here is my thought. If i know my coordinates when the piece is grabbed, Could i put in some coordinates that would be a straight line away from the coordinates i am currently at?

its a bit of a weird setup. the arm is mounted at a 45 degree angle as are the parts/pegs.

I'll gladly provide more info as necessary. I think what i am mainly looking for right now is the correct equation to use and how to incorporate all the variables correctly.

Thank you!
 

Papabravo

Joined Feb 24, 2006
14,867
Hi all,

This might be a bit simple, (Calculus 3 if i remember right?)

Here is my problem. I am running into a problem when my arm after it grabs something. My parts on on little pegs and the arm isn't pulling the part off exactly straight. I get a torque on the wrist when this happens and the program doesn't like that one bit.

Here is my thought. If i know my coordinates when the piece is grabbed, Could i put in some coordinates that would be a straight line away from the coordinates i am currently at?

its a bit of a weird setup. the arm is mounted at a 45 degree angle as are the parts/pegs.

I'll gladly provide more info as necessary. I think what i am mainly looking for right now is the correct equation to use and how to incorporate all the variables correctly.

Thank you!
I think you want the parametric equations of a line:
\[ x\;=\;x_0+at\\y\;=\;y_0+bt\\z\;=\;z_0+ct \]
Let a, b, c be the destination point and run t from 0 to 1 in any convenient step size. You can pre-calculate the individual moves and just output them at each 'tick' of your velocity clock.
 
Last edited:

cmartinez

Joined Jan 17, 2007
7,223
A while ago I did some parametric programming for ABB robotic arms. What I can tell you is that in order to draw a straight line with them you need to use what are called quaternions. And most of the time a simple movement has more than one solution. That is, there's more than one way to obtain the same thing.

I suggest you do a little digging on quaternions and learn how they work.
 
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